1. Field of the Invention
The present invention generally relates to magnetic recording media and magnetic storage apparatuses, and more particularly to a longitudinal magnetic recording medium which uses a thermally unstable layer to stabilize a recording magnetic layer for improving the thermal stability of the recording magnetic layer, and to a magnetic storage apparatus which uses such a magnetic recording medium.
2. Description of the Related Art
The demand for increased storage capacity of magnetic recording media has resulted in the development of the magnetic thin film disk by suitable scaling of both growth and magnetic properties, and also innovations in designing, as may be understood from recently developed Synthetic Ferrimagnetic Media (SFM) proposed in a Japanese Laid-Open Patent Application No. 2001-56924, and findings reported in Abarra et al., “Longitudinal magnetic recording media with thermal stabilization layers”, Applied Physics Letters, Vol. 77, No. 16, pp. 2581-2583, Oct. 15, 2000, and Fullerton et al., “Antiferromagnetically coupled magnetic media layers for thermally stable high-density recording”, Applied Physics Letters, Vol.77, No.23, pp.3806-3808, Dec. 4, 2000.
As the magnetic recording density become very high and the amount of information stored per unit area becomes extremely large, the requirement of scaling down on the magnetic recording layer dimension is unavoidable. Making the magnetic recording layer thinner is advantageous in reducing the grain sizes and also reducing the transition parameter accordingly. However, this cannot go on for long since the grain size reduction and hence the reduction in anisotropy energy becomes too small which can be easily overcome by thermal energy at a given temperature (normally room temperature). In order to achieve alternative approaches in design, it is necessary to further improve the magnetic recording medium such as the synthetic ferrimagnetic media proposed in the Japanese Laid-Open Patent Application No.2001-56924.